oil pressure 5.7L conversion

first off, thanks for those that take the time to read this and reply.
Im the owner (not builder ) of a 91 S-10 blazer that was converted from a 4.3L to a 5.7L 350 engine. Im pulling the pan tomorrow to
change out the oil pump to a high volume one because the oil pressure at startup is about 20-35 lbs at idle and drops to about 10lbs after warm. 2k rpm is about 25 lbs pressure again. This is going to be an all day job because of all the stuff in the way of getting the pan down.
Ok, can someone please tell me whats going on here. I rev up the engine, and then right when i let off the accellerator the oil pressure will jump up about 5 pounds. any clues to whats causing this?
THanks Again -Eric White
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If it jumps up and not down when you let off the gas, it's loose main bearings. Or at least it could be. Did you put a real oil pressure gauge on it or are you reading the stock gauge? Before you pull anything apart be sure to check it with a real gauge.
Al
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snipped-for-privacy@hotmail.com wrote:

All your symptoms sound like worn out crankshaft bearings.
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wrote:

I agree, a bigger oil pump is not going to fix worn bearings. A 350 has a fine stock oiling system by design and it fails only from neglect or abuse (and it takes a lot of abuse too). Replace the main and rod bearings and forget the oil pump if you really want it to last for a while.

TheSnoMan.com
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snipped-for-privacy@hotmail.com wrote:

Pull the pan, replace the main and rod bearings and put a good stock pump back in. The stock 350 pump will handle it no problem. What you are seeing is the result of worn bearings.
--
Steve W.
Near Cooperstown, New York
  Click to see the full signature.
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Thanks to all the helpers. I ended up replacint the stock pump with a high volume one and used 30wt castrol oil. pressure is now 40 at 2k rpm and 20-25 at idle. It too litterally 12 hrs to replace this pump because of all the shit that had to be removed, engine mounts removed, engine jacked up and misc other issues just to get the pan to release. To top it all off, now i have a gasket leak in the pan......sigh......
Thanks gang -eric
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snipped-for-privacy@hotmail.com wrote:

Please come back and let us know how many miles you get out of it.
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i know i know, its not a fix to the problem but only a band-aid. I bought the truck as a quick fix to needing a vehicle to drive for my delivery route. I really do not intend on keeping the truck more than a few months so i can save back a little cash to buy another in far better condition. This is a whole lot more power than i care for or need but it runs good, sounds good, doesnt burn oil or leak any now - remote oil unit was the culprit. I was seaking info to make a decision on keep the vehicle and rebuild the engine, or drive as is ans sell. Im going to sell if its still in 1 piece in 5 months.
THanks again -Eric
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